<!-- 动态星空 -->
<template>
  <div class="body">
    <div class="stars" ref="starsRef">
      <div class="star" v-for="(item, index) in starsCount" :key="index"></div>
    </div>
  </div>
</template>

<script>
import { onMounted, ref } from "vue";

export default {
  data () {
    return {
      starsCount: 800, //星星数量
      distance: 800 //间距
    }
  },
  setup() {
    let starsRef = ref(null);

    // var starsCount = 800; //星星数量
    // const distance = 900; //间距

    onMounted(() => {
      let starNodes = Array.from(starsRef.value.children);
      starNodes.forEach((item) => {
        let speed = 0.2 + Math.random() * 1;
        let thisDistance = distance + Math.random() * 300;
        item.style.transformOrigin = `0 0 ${thisDistance}px`;
        item.style.transform = `
        translate3d(0,0,-${thisDistance}px)
        rotateY(${Math.random() * 360}deg)
        rotateX(${Math.random() * -50}deg)
        scale(${speed},${speed})`;
      });
    });

    return {
      starsRef,
      starsCount,
    };
  },
};

// export default {
//   data() {
//     return {
//       starsCount: 800, //星星数量
//       distance: 800 //间距
//     };
//   },
//   mounted(){
//     let starArr = this.$refs.star
//     starArr.forEach(item = {
//       let speed = 0.2 + (Math.random() * 1);
//       let thisDistance = this.distance + (Math.random() * 300);
//       item.style.transformOrigin = `0 0 ${thisDistance}px`;
//       item.style.transform = `
//         translate3d(0,0,-${thisDistance}px)
//         rotateY(${Math.random() * 360}deg)
//         rotateX(${Math.random() * -50}deg)
//         scale(${speed},${speed})`;
//     })
//   }
// };
</script>

<style lang="css" scoped>
.body {
  position: absolute;
  width: 100%;
  height: 100%;
  margin: 0;
  padding: 0;
  background: radial-gradient(
    200% 100% at bottom center,
    #f7f7b6,
    #e96f92,
    #1b2947
  );
  background: radial-gradient(
    200% 105% at top center,
    #1b2947 10%,
    #75517d 40%,
    #e96f92 65%,
    #f7f7b6
  );
  background-attachment: fixed;
  overflow: hidden;
}

@keyframes rotate {
  0% {
    transform: perspective(400px) rotateZ(20deg) rotateX(-40deg) rotateY(0);
  }
  100% {
    transform: perspective(400px) rotateZ(20deg) rotateX(-40deg)
      rotateY(-360deg);
  }
}
.stars {
  transform: perspective(500px);
  transform-style: preserve-3d;
  position: absolute;
  perspective-origin: 50% 100%;
  left: 45%;
  animation: rotate 90s infinite linear;
  bottom: 0;
}
.star {
  width: 2px;
  height: 2px;
  background: #f7f7b6;
  position: absolute;
  left: 0;
  top: 0;
  backface-visibility: hidden;
}
</style>
